Medical device with triggered blanking period

ABSTRACT

An implantable cardiac rhythm system includes a first implantable medical device configured to detect a first heartbeat from a first location, and a second implantable medical device configured to detect the first heart beat of the patient from a second location. The second implantable medical device, upon detecting the first heart beat, may communicate an indication of the detected first heart beat to the first implantable medical device, and in response, the first implantable medical device may institute a blanking period having a blanking period duration such that a T-wave of the detected first heart beat is blanked out by the first implantable medical device so as to not be interpreted as a subsequent second heart beat. In some instances, the first implantable medical device is an SICD and the second implantable medical device is a LCP.

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional Patent Application Ser. No. 62/043,106 filed Aug. 28, 2014, the disclosures of each incorporated herein by reference.

TECHNICAL FIELD

The present disclosure generally relates to implantable medical devices and more particularly to methods and systems for improving the effectiveness of implantable medical devices.

BACKGROUND

Pacing instruments can be used to treat patients suffering from various heart conditions that may result in a reduced ability of the heart to deliver sufficient amounts of blood to a patient's body. These heart conditions may lead to rapid, irregular, and/or inefficient heart contractions. To help alleviate some of these conditions, various devices (e.g., pacemakers, defibrillators, sensors, etc.) can be implanted in a patient's body. Such devices may monitor and provide electrical stimulation to the heart to help the heart operate in a more normal, efficient and/or safe manner. In some cases, a patient may have multiple implanted devices that are configured to communicate to help monitor a patient's condition and/or deliver an effective therapy.

SUMMARY

The present disclosure generally relates to implantable medical devices and more particularly to methods and systems for improving the effectiveness of implantable medical devices.

In a first example, an implantable cardiac rhythm system includes a first implantable medical device that is configured to monitor a patient's heart rhythm and provide shock therapy to correct the patient's heart rhythm, and a second implantable medical device that is configured to at least sense the patient's heart. The first implantable medical device is configured to detect a first heart beat of the patient from a first location, and the second implantable medical device is configured to detect the first heart beat of the patient from a second location. The second implantable medical device, upon detecting the first heart beat, may communicate an indication of the detected first heart beat to the first implantable medical device, and in response, the first implantable medical device may institute a blanking period having a blanking period duration such that a T-wave of the detected first heart beat is blanked out by the first implantable medical device so as to not be interpreted as a subsequent second heart beat.

Alternatively, or additionally, and in a second example, the first implantable medical device of the first example includes a defibrillator or cardioverter.

Alternatively, or additionally, and in a third example, the first implantable medical device of the first or second example includes a subcutaneous cardioverter.

Alternatively, or additionally, and in a fourth example, the second implantable medical device of any of the first through third examples includes a leadless cardiac pacemaker.

Alternatively, or additionally, and in a fifth example, the second implantable medical device of any of the first through fourth examples communicates with the first implantable medical device via conducted communication.

Alternatively, or additionally, and in a sixth example, the communicated indication of the detected first heart beat of any of the first through fifth examples includes an R-wave detection marker.

Alternatively, or additionally, and in a seventh example, the blanking period duration of any of the first through sixth examples is set based, at least in part, upon a current heart rate detected by one or both of the first implantable medical device and the second implantable medical device.

Alternatively, or additionally, and in an eighth example, the blanking period duration of any of the first through seventh examples is set based, at least in part, upon whether the detected first heart beat is an intrinsic heart beat or a paced heart beat.

Alternatively, or additionally, and in a ninth example, wherein upon receiving the indication of the detected first heart beat from the second implantable medical device, the first implantable medical device of any of the first through eighth examples continues to attempt to detect the first heart beat of the patient from the first location for a blanking time delay before instituting the blanking period.

Alternatively, or additionally, and in a tenth example, the blanking time delay of any of the first through ninth examples is dependent upon a current heart rate of the patient.

Alternatively, or additionally, and in an eleventh example, in the implantable cardiac rhythm system of any of the first through tenth examples, the first location is outside of the patient's heart and the second location is within the patient's heart.

Alternatively, or additionally, and in a twelfth example, in the implantable cardiac rhythm system of the eleventh example, the first location is outside of the patient's chest cavity, and the second location is within a chamber of the patient's heart.

Example thirteen is an implantable medical device that includes one or more electrodes for detecting a heart beat of a patient and a receiver for receiving via conducted communication from another medical device an indication of a detected heart beat. The implantable medical device, in response to receiving the indication of the detected heart beat, institutes a blanking period having a blanking period duration. The implantable medical device is configured to not identify a subsequent heart beat of the patient via the one or more electrodes of the implantable medical device during the blanking period duration.

Alternatively, or additionally, and in a fourteenth example, in response to receiving the indication of the detected heart beat, the implantable medical device of the thirteenth example continues to sense for the heart beat of the patient for a blanking time delay before instituting the blanking period.

Alternatively, or additionally, and in a fifteenth example, in the implantable medical device of any of the thirteenth or fourteenth example, the blanking period duration is set based, at least in part, upon a current heart rate of the patient.

Alternatively, or additionally, and in a sixteenth example, in the implantable medical device of any of the thirteenth through fifteenth examples, the blanking period duration is set based, at least in part, upon whether the detected heart beat is an intrinsic heart beat or a paced heart beat.

Alternatively, or additionally, and in a seventeenth example, the implantable medical device of any of the thirteenth through sixteenth examples is a subcutaneous implantable cardioverter, and the another medical device is a leadless cardiac pacemaker.

Alternatively, or additionally, and in an eighteenth example, in the implantable medical device of any of the thirteenth through seventeenth examples, the received indication of the detected heart beat comprises an R-wave detection marker.

Example nineteen is a method of using data from a leadless cardiac pacemaker to improve performance of a subcutaneous implantable cardioverter. A first heart beat is detected via the leadless cardiac pacemaker. The first heart beat is detected via the subcutaneous implantable cardioverter. An indication of the detected first heart beat detected by the leadless cardiac pacemaker is communicated to the subcutaneous implantable cardioverter. The subcutaneous implantable cardioverter initiated a blanking period such that a T-wave of the detected first heart beat is blanked out by the subcutaneous implantable cardioverter so as to not be interpreted as a subsequent second heart beat

Alternatively, or additionally, and in a twentieth example, the blanking period of the nineteenth example is configured such that a subsequent heart beat would be seen by the subcutaneous implantable cardioverter.

The above summary is not intended to describe each embodiment or every implementation of the present disclosure. Advantages and attainments, together with a more complete understanding of the disclosure, will become apparent and appreciated by referring to the following description and claims taken in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

The disclosure may be more completely understood in consideration of the following description of various illustrative embodiments in connection with the accompanying drawings, in which:

FIG. 1 is a schematic illustration of an implantable cardiac rhythm system according to an example of the present disclosure;

FIG. 2 is a graph illustrating use of the implantable cardiac rhythm system of FIG. 1;

FIG. 3 is a graph illustrating use of the implantable cardiac rhythm system of FIG. 1;

FIG. 4 is a schematic diagram of an implantable medical device according to an example of the present disclosure;

FIG. 5 is a schematic block diagram of an illustrative leadless cardiac pacemaker (LCP) according to one example of the present disclosure;

FIG. 6 is a schematic block diagram of another illustrative medical device that may be used in conjunction with the LCP of FIG. 5;

FIG. 7 is a schematic diagram of an exemplary medical system that includes multiple LCPs and/or other devices in communication with one another;

FIG. 8 is a schematic diagram of a system including an LCP and another medical device, in accordance with yet another example of the present disclosure;

FIG. 9 is a schematic diagram of a system including an LCP and another medical device, in accordance with another example of the present disclosure; and

FIG. 10 is a flow diagram of an illustrative method that may be implemented by a medical device such as those illustrated in FIGS. 1-8.

While the disclosure is amenable to various modifications and alternative forms, specifics thereof have been shown by way of example in the drawings and will be described in detail. It should be understood, however, that the intention is not to limit aspects of the disclosure to the particular illustrative embodiments described. On the contrary, the intention is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the disclosure.

DESCRIPTION

The following description should be read with reference to the drawings in which similar elements in different drawings are numbered the same. The description and the drawings, which are not necessarily to scale, depict illustrative embodiments and are not intended to limit the scope of the disclosure.

A normal, healthy heart induces contraction by conducting intrinsically generated electrical signals throughout the heart. These intrinsic signals cause the muscle cells or tissue of the heart to contract. This contraction forces blood out of and into the heart, providing circulation of the blood throughout the rest of the body. However, many patients suffer from cardiac conditions that affect this contractility of their hearts. For example, some hearts may develop diseased tissues that no longer generate or conduct intrinsic electrical signals. In some examples, diseased cardiac tissues conduct electrical signals at differing rates, thereby causing an unsynchronized and inefficient contraction of the heart. In other examples, a heart may generate intrinsic signals at such a low rate that the heart rate becomes dangerously low. In still other examples, a heart may generate electrical signals at an unusually high rate. In some cases such an abnormality can develop into a fibrillation state, where the contraction of the patient's heart chambers are almost completely de-synchronized and the heart pumps very little to no blood. Implantable medical device which may be configured to determine occurrences of such cardiac abnormalities or arrhythmias and deliver one or more types of electrical stimulation therapy to patient's hearts may help to terminate or alleviate such cardiac conditions.

A variety of different medical devices, including various implantable medical devices, may be deployed to monitor cardiac events and to provide therapy when appropriate. FIG. 1 provides a schematic illustration of an implantable cardiac rhythm system 10 that includes a first implantable device 12 and a second implantable device 14. In some embodiments, first implantable device 12 may be configured to monitor a patient's heart rhythm and provide shock therapy to correct the patient's heart rhythm. In some embodiments, second implantable device 14 may be configured to sense (and sometimes pace) the patient's heart.

First implantable device 12 may be configured to detect a first heart beat of the patient from a first location, while second implantable device 14 may be configured to detect the same first heart beat of the patient from a second location, wherein the second location is different from the first location. For example, in some embodiments, the first location is outside of the patient's heart while the second location is within the patient's heart. In some embodiments, the first location is outside of the patient's chest cavity and the second location is within a chamber of the patient's heart. Once second implantable device 14 detects the first heart beat, second implantable device 14 may communicate an indication of the detected first heart beat to first implantable device 12, and in response first implantable device 12 may institute a blanking period having a blanking period duration such that a T-wave of the detected first heart beat is blanked out by first implantable device 12 so as to not be interpreted as a subsequent second heart beat. In some embodiments, second implantable device 14 communicates with first implantable device 12 via conducted communication. In some embodiments, the communicated indication of the detected first heart beat, communicated from second implantable device 14 to first implantable device 12, includes an R-wave detection marker. The R-wave detection marker may inform the first implantable device 12 of the occurrence of an R-wave of the first heart beat detected by the second implantable device 14, and in some cases when the R-wave occurred (i.e. via a timestamp or the like). In some cases, the R-wave detection marker may provide additional information, such as the current detected heart beat rate (e.g. such as time between the previous and the current detected R-waves) and/or any other suitable information.

First implantable device 12 and second implantable device 14 may be any desired implantable devices. In some embodiments, first implantable device 12 may be a defibrillator or cardioverter. In some embodiments, first implantable device 12 may be a subcutaneous cardioverter, with sense electrodes placed outside of the chest cavity. In some embodiments, second implantable device 14 may be a leadless cardiac pacemaker placed in or on the heart.

Illustrative blanking periods are illustrated with respect to FIGS. 2 and 3. FIG. 2 provides an LCP (leadless cardiac pacemaker) electrocardiogram 16, corresponding LCP R-wave sense events 18, an SICD (subcutaneous implantable cardioverter) electrocardiogram 20 and SICD blanking periods 22. In FIG. 2, two R-wave sense events are shown, followed by an R-wave pace event and then another R-wave sense event. It will be appreciated that the LCP and SICD electrocardiograms 16, 20 shown in FIG. 2 are stylized and do not represent actual patient data. By comparing the blanking period 22 for a particular sense or pace event to the SICD electrocardiogram 20, it can be seen that the blanking period 22 is of a duration (denoted as “x”) that the ensuing T-wave cannot be picked up or considered by the SICD as being an R-wave of a subsequent heart beat. In some embodiments, as shown, the blanking period 22 associated with a pace event may have a different duration (denoted as “y”).

In some embodiments, the blanking period may not start immediately, but may be delayed a delay period of time after the second implantable device 14 (FIG. 1) senses an event, or creates a pace event. In some embodiments, this delay permits the SICD to properly sense and classify the R-wave of the heart beat and yet still place the T-wave in the blanking period. This is illustrated in FIG. 3, which includes LCP electrocardiogram 16, LCP R-wave sense events 18, SICD electrocardiogram 20 and SICD blanking periods 24. In FIG. 3, two R-wave sense events are shown, followed by an R-wave pace event and then another R-wave sense event. The blanking periods have a delay (denoted by “z” in FIG. 3) that enables the R-wave of the current heart beat to be outside of the blanking period, and thus the R-wave can be considered by the SICD.

In some embodiments, the blanking period duration is set based, at least in part, upon a current heart rate detected by one or both of first implantable device 12 and second implantable device 14. For example, as the heart rate increases, the duration of the blanking period may decrease. Examples of illustrative blanking period durations include about 90 to about 110 milliseconds (mS), or about 95 to about 105 mS, at a heart rate of 60 beats per minute (bpm) and about 70 to 90 mS, or about 75 to about 85 mS, at a heart rate of 120 bpm. In some embodiments, an illustrative blanking period duration may be about 100 milliseconds (mS) at a heart rate of 60 beats per minute (bpm) and about 80 mS at 120 bpm.

The blanking period duration may depend, at least in part, upon whether the detected heart beat is an intrinsic heartbeat or a paced heartbeat. In some embodiments, upon receiving the indication of the detected first heartbeat from second implantable device 14, first implantable device 12 may continue to attempt to detect the first heartbeat of the patient from the first location for a blanking time delay before instituting the blanking period. The blanking time delay may be in the range of 100 to 300 mS. In some cases, the blanking time delay may be dependent upon a current heart rate of the patient. For example, as the heart rate increases, the delay before the blanking period may decrease.

FIG. 4 is a schematic illustration of an implantable medical device 26 that includes one or more (two are illustrated) electrodes 28 for detecting a heartbeat of a patient as well as a receiver 30 for receiving, via conducted communication from another medical device, an indication of a detected heartbeat (e.g. an R-wave detection marker). While the illustrative embodiment shown uses the same electrodes 28 for detecting a heartbeat and for communication, it is contemplated that separate electrodes may be provided for detecting a heartbeat and for communication. In any event, implantable medical device 26 may be configured such that, in response to receiving the indication of the detected heartbeat via the electrodes 28, a blanking period having a blanking period duration may be instituted, during which implantable medical device 26 blanks out, or does not identify, a subsequent heartbeat of the patient via the one or more electrodes 28.

In some embodiments, the blanking period duration is set based, at least in part, upon a current heart rate of the patient and/or upon whether the detected heart beat is an intrinsic heart beat or a paced heartbeat. The received indication of the detected heartbeat may, in some cases, include an R-wave detection marker. In some embodiments, implantable medical device 26 may be a subcutaneous implantable cardioverter, and thus may be an example of first implantable device 12 (FIG. 1), while the other medical device may be a leadless cardiac pacemaker, and hence an example of second implantable device 14.

FIG. 5 depicts an exemplary leadless cardiac pacemaker (LCP) that may be implanted into a patient and may operate to deliver appropriate therapy to the heart, such as to deliver anti-tachycardia pacing (ATP) therapy, cardiac resynchronization therapy (CRT), bradycardia therapy, and/or the like. As can be seen in FIG. 5, LCP 100 may be a compact device with all components housed within LCP 100 or directly on housing 120. In the example shown in FIG. 5, LCP 100 may include a communication module 102, a pulse generator module 104, an electrical sensing module 106, a mechanical sensing module 108, a processing module 110, a battery 112, and electrodes 114. LCP 100 may include more or less modules, depending on the application.

Communication module 102 may be configured to communicate with devices such as sensors, other medical devices such as an SICD, and/or the like, that are located externally to LCP 100. Such devices may be located either external or internal to the patient's body. Irrespective of the location, external devices (i.e. external to the LCP 100 but not necessarily external to the patient's body) can communicate with LCP 100 via communication module 102 to accomplish one or more desired functions. For example, LCP 100 may communicate information, such as sensed electrical signals, data, instructions, messages, R-wave detection markers, etc., to an external medical device through communication module 102. The external medical device may use the communicated signals, data, instructions, messages, R-wave detection markers, etc., to perform various functions, such as determining occurrences of arrhythmias, delivering electrical stimulation therapy, storing received data, and/or performing any other suitable function. LCP 100 may additionally receive information such as signals, data, instructions and/or messages from the external medical device through communication module 102, and LCP 100 may use the received signals, data, instructions and/or messages to perform various functions, such as determining occurrences of arrhythmias, delivering electrical stimulation therapy, storing received data, and/or performing any other suitable function. Communication module 102 may be configured to use one or more methods for communicating with external devices. For example, communication module 102 may communicate via radiofrequency (RF) signals, inductive coupling, optical signals, acoustic signals, conducted communication signals, and/or any other signals suitable for communication.

In the example shown in FIG. 5, pulse generator module 104 may be electrically connected to electrodes 114. In some examples, LCP 100 may additionally include electrodes 114′. In such examples, pulse generator 104 may also be electrically connected to electrodes 114′. Pulse generator module 104 may be configured to generate electrical stimulation signals. For example, pulse generator module 104 may generate electrical stimulation signals by using energy stored in battery 112 within LCP 100 and deliver the generated electrical stimulation signals via electrodes 114 and/or 114′. Alternatively, or additionally, pulse generator 104 may include one or more capacitors, and pulse generator 104 may charge the one or more capacitors by drawing energy from battery 112. Pulse generator 104 may then use the energy of the one or more capacitors to deliver the generated electrical stimulation signals via electrodes 114 and/or 114′. In at least some examples, pulse generator 104 of LCP 100 may include switching circuitry to selectively connect one or more of electrodes 114 and/or 114′ to pulse generator 104 in order to select which electrodes 114/114′ (and/or other electrodes) pulse generator 104 delivers the electrical stimulation therapy. Pulse generator module 104 may generate electrical stimulation signals with particular features or in particular sequences in order to provide one or multiple of a number of different stimulation therapies. For example, pulse generator module 104 may be configured to generate electrical stimulation signals to provide electrical stimulation therapy to combat bradycardia, tachycardia, cardiac synchronization, bradycardia arrhythmias, tachycardia arrhythmias, fibrillation arrhythmias, cardiac synchronization arrhythmias and/or to produce any other suitable electrical stimulation therapy. Some more common electrical stimulation therapies include anti-tachycardia pacing (ATP) therapy, cardiac resynchronization therapy (CRT), and cardioversion/defibrillation therapy.

In some examples, LCP 100 may not include a pulse generator 104. For example, LCP 100 may be a diagnostic only device. In such examples, LCP 100 may not deliver electrical stimulation therapy to a patient. Rather, LCP 100 may collect data about cardiac electrical activity and/or physiological parameters of the patient and communicate such data and/or determinations to one or more other medical devices via communication module 102.

In some examples, LCP 100 may include an electrical sensing module 106, and in some cases, a mechanical sensing module 108. Electrical sensing module 106 may be configured to sense the cardiac electrical activity of the heart. For example, electrical sensing module 106 may be connected to electrodes 114/114′, and electrical sensing module 106 may be configured to receive cardiac electrical signals conducted through electrodes 114/114′. The cardiac electrical signals may represent local information from the chamber in which LCP 100 is implanted. For instance, if LCP 100 is implanted within a ventricle of the heart, cardiac electrical signals sensed by LCP 100 through electrodes 114/114′ may represent ventricular cardiac electrical signals. Mechanical sensing module 108 may include one or more sensors, such as an accelerometer, a blood pressure sensor, a heart sound sensor, a blood-oxygen sensor, a temperature sensor, a flow sensor and/or any other suitable sensors that are configured to measure one or more mechanical/chemical parameters of the patient. Both electrical sensing module 106 and mechanical sensing module 108 may be connected to a processing module 110, which may provide signals representative of the sensed mechanical parameters. Although described with respect to FIG. 5 as separate sensing modules, in some cases, electrical sensing module 206 and mechanical sensing module 208 may be combined into a single sensing module, as desired.

Electrodes 114/114′ can be secured relative to housing 120 but exposed to the tissue and/or blood surrounding LCP 100. In some cases, electrodes 114 may be generally disposed on either end of LCP 100 and may be in electrical communication with one or more of modules 102, 104, 106, 108, and 110. Electrodes 114/114′ may be supported by the housing 120, although in some examples, electrodes 114/114′ may be connected to housing 120 through short connecting wires such that electrodes 114/114′ are not directly secured relative to housing 120. In examples where LCP 100 includes one or more electrodes 114′, electrodes 114′ may in some cases be disposed on the sides of LCP 100, which may increase the number of electrodes by which LCP 100 may sense cardiac electrical activity, deliver electrical stimulation and/or communicate with an external medical device. Electrodes 114/114′ can be made up of one or more biocompatible conductive materials such as various metals or alloys that are known to be safe for implantation within a human body. In some instances, electrodes 114/114′ connected to LCP 100 may have an insulative portion that electrically isolates electrodes 114/114′ from adjacent electrodes, housing 120, and/or other parts of the LCP 100.

Processing module 110 can be configured to control the operation of LCP 100. For example, processing module 110 may be configured to receive electrical signals from electrical sensing module 106 and/or mechanical sensing module 108. Based on the received signals, processing module 110 may determine, for example, occurrences and, in some cases, types of arrhythmias. Based on any determined arrhythmias, processing module 110 may control pulse generator module 104 to generate electrical stimulation in accordance with one or more therapies to treat the determined arrhythmia(s). Processing module 110 may further receive information from communication module 102. In some examples, processing module 110 may use such received information to help determine whether an arrhythmia is occurring, determine a type of arrhythmia, and/or to take particular action in response to the information. Processing module 110 may additionally control communication module 102 to send/receive information to/from other devices.

In some examples, processing module 110 may include a pre-programmed chip, such as a very-large-scale integration (VLSI) chip and/or an application specific integrated circuit (ASIC). In such embodiments, the chip may be pre-programmed with control logic in order to control the operation of LCP 100. By using a pre-programmed chip, processing module 110 may use less power than other programmable circuits (e.g. general purpose programmable microprocessors) while still being able to maintain basic functionality, thereby potentially increasing the battery life of LCP 100. In other examples, processing module 110 may include a programmable microprocessor. Such a programmable microprocessor may allow a user to modify the control logic of LCP 100 even after implantation, thereby allowing for greater flexibility of LCP 100 than when using a pre-programmed ASIC. In some examples, processing module 110 may further include a memory, and processing module 110 may store information on and read information from the memory. In other examples, LCP 100 may include a separate memory (not shown) that is in communication with processing module 110, such that processing module 110 may read and write information to and from the separate memory.

Battery 112 may provide power to the LCP 100 for its operations. In some examples, battery 112 may be a non-rechargeable lithium-based battery. In other examples, a non-rechargeable battery may be made from other suitable materials, as desired. Because LCP 100 is an implantable device, access to LCP 100 may be limited after implantation. Accordingly, it is desirable to have sufficient battery capacity to deliver therapy over a period of treatment such as days, weeks, months, years or even decades. In some instances, battery 110 may a rechargeable battery, which may help increase the useable lifespan of LCP 100. In still other examples, battery 110 may be some other type of power source, as desired.

To implant LCP 100 inside a patient's body, an operator (e.g., a physician, clinician, etc.), may fix LCP 100 to the cardiac tissue of the patient's heart. To facilitate fixation, LCP 100 may include one or more anchors 116. Anchor 116 may include any one of a number of fixation or anchoring mechanisms. For example, anchor 116 may include one or more pins, staples, threads, screws, helix, tines, and/or the like. In some examples, although not shown, anchor 116 may include threads on its external surface that may run along at least a partial length of anchor 116. The threads may provide friction between the cardiac tissue and the anchor to help fix the anchor 116 within the cardiac tissue. In other examples, anchor 116 may include other structures such as barbs, spikes, or the like to facilitate engagement with the surrounding cardiac tissue.

FIG. 6 depicts an example of another medical device (MD) 200, which may be used in conjunction with LCP 100 (FIG. 5) in order to detect and/or treat cardiac arrhythmias and other heart conditions. In the example shown, MD 200 may include a communication module 202, a pulse generator module 204, an electrical sensing module 206, a mechanical sensing module 208, a processing module 210, and a battery 218. Each of these modules may be similar to modules 102, 104, 106, 108, and 110 of LCP 100. Additionally, battery 218 may be similar to battery 112 of LCP 100. In some examples, however, MD 200 may have a larger volume within housing 220. In such examples, MD 200 may include a larger battery and/or a larger processing module 210 capable of handling more complex operations than processing module 110 of LCP 100.

While it is contemplated that MD 200 may be another leadless device such as shown in FIG. 5, in some instances MD 200 may include leads such as leads 212. Leads 212 may include electrical wires that conduct electrical signals between electrodes 214 and one or more modules located within housing 220. In some cases, leads 212 may be connected to and extend away from housing 220 of MD 200. In some examples, leads 212 are implanted on, within, or adjacent to a heart of a patient. Leads 212 may contain one or more electrodes 214 positioned at various locations on leads 212, and in some cases at various distances from housing 220. Some leads 212 may only include a single electrode 214, while other leads 212 may include multiple electrodes 214. Generally, electrodes 214 are positioned on leads 212 such that when leads 212 are implanted within the patient, one or more of the electrodes 214 are positioned to perform a desired function. In some cases, the one or more of the electrodes 214 may be in contact with the patient's cardiac tissue. In some cases, the one or more of the electrodes 214 may be positioned subcutaneously but adjacent the patient's heart. In some cases, electrodes 214 may conduct intrinsically generated electrical signals to leads 212, e.g. signals representative of intrinsic cardiac electrical activity. Leads 212 may, in turn, conduct the received electrical signals to one or more of the modules 202, 204, 206, and 208 of MD 200. In some cases, MD 200 may generate electrical stimulation signals, and leads 212 may conduct the generated electrical stimulation signals to electrodes 214. Electrodes 214 may then conduct the electrical signals and delivery the signals to the patient's heart (either directly or indirectly).

Mechanical sensing module 208, as with mechanical sensing module 108, may contain or be electrically connected to one or more sensors, such as accelerometers, blood pressure sensors, heart sound sensors, blood-oxygen sensors, and/or other sensors which are configured to measure one or more mechanical/chemical parameters of the heart and/or patient. In some examples, one or more of the sensors may be located on leads 212, but this is not required. In some examples, one or more of the sensors may be located in housing 220.

While not required, in some examples, MD 200 may be an implantable medical device. In such examples, housing 220 of MD 200 may be implanted in, for example, a transthoracic region of the patient. Housing 220 may generally include any of a number of known materials that are safe for implantation in a human body and may, when implanted, hermetically seal the various components of MD 200 from fluids and tissues of the patient's body.

In some cases, MD 200 may be an implantable cardiac pacemaker (ICP). In this example, MD 200 may have one or more leads, for example leads 212, which are implanted on or within the patient's heart. The one or more leads 212 may include one or more electrodes 214 that are in contact with cardiac tissue and/or blood of the patient's heart. MD 200 may be configured to sense intrinsically generated cardiac electrical signals and determine, for example, one or more cardiac arrhythmias based on analysis of the sensed signals. MD 200 may be configured to deliver CRT, ATP therapy, bradycardia therapy, and/or other therapy types via leads 212 implanted within the heart. In some examples, MD 200 may additionally be configured provide defibrillation therapy.

In some instances, MD 200 may be an implantable cardioverter-defibrillator (ICD). In such examples, MD 200 may include one or more leads implanted within a patient's heart. MD 200 may also be configured to sense cardiac electrical signals, determine occurrences of tachyarrhythmias based on the sensed signals, and may be configured to deliver defibrillation therapy in response to determining an occurrence of a tachyarrhythmia. In other examples, MD 200 may be a subcutaneous implantable cardioverter-defibrillator (S-ICD). In examples where MD 200 is an S-ICD, one of leads 212 may be a subcutaneously implanted lead. In at least some examples where MD 200 is an S-ICD, MD 200 may include only a single lead which is implanted subcutaneously, but this is not required. In some instances, the lead(s) may have one or more electrodes that are placed subcutaneously and outside of the chest cavity. In other examples, the lead(s) may have one or more electrodes that are placed inside of the chest cavity.

In some examples, MD 200 may not be an implantable medical device. Rather, MD 200 may be a device external to the patient's body, and may include skin-electrodes that are placed on a patient's body. In such examples, MD 200 may be able to sense surface electrical signals (e.g. cardiac electrical signals that are generated by the heart or electrical signals generated by a device implanted within a patient's body and conducted through the body to the skin). In such examples, MD 200 may be configured to deliver various types of electrical stimulation therapy, including, for example, defibrillation therapy.

In an example, blanking may be defined as medical device 100 or/and medical device 200 ignoring all information from electrical sensing module 106 and/or electrical sensing module 206 respectively during a blanking period. In another example, blanking includes disconnecting one or more electrodes 114/114′ and/or electrodes 214 from electrical sensing module 106 and/or electrical sensing module 206 respectively during a blanking period. In yet another example, blanking includes removing power from electrical sensing module 106 and/or electrical sensing module 206 during a blanking period. In still another example, blanking includes connecting one or more electrodes 114/114′ and/or electrodes 214 to an electrical signal ground during a blanking period. In a further example, blanking includes a combination of one or more of the examples described above during a blanking period.

FIG. 7 illustrates an example of a medical device system and a communication pathway through which multiple medical devices 302, 304, 306, and/or 310 may communicate. In the example shown, medical device system 300 may include LCPs 302 and 304, external medical device 306, and other sensors/devices 310. External device 306 may be any of the devices described previously with respect to MD 200. Other sensors/devices 310 may also be any of the devices described previously with respect to MD 200. In some instances, other sensors/devices 310 may include a sensor, such as an accelerometer or blood pressure sensor, or the like. In some cases, other sensors/devices 310 may include an external programmer device that may be used to program one or more devices of system 300.

Various devices of system 300 may communicate via communication pathway 308. For example, LCPs 302 and/or 304 may sense intrinsic cardiac electrical signals and may communicate such signals to one or more other devices 302/304, 306, and 310 of system 300 via communication pathway 308. In one example, one or more of devices 302/304 may receive such signals and, based on the received signals, determine an occurrence of an arrhythmia. In some cases, device or devices 302/304 may communicate such determinations to one or more other devices 306 and 310 of system 300. In some cases, one or more of devices 302/304, 306, and 310 of system 300 may take action based on the communicated determination of an arrhythmia, such as by delivering a suitable electrical stimulation to the heart of the patient. It is contemplated that communication pathway 308 may communicate using RF signals, inductive coupling, optical signals, acoustic signals, or any other signals suitable for communication. Additionally, in at least some examples, device communication pathway 308 may comprise multiple signal types. For instance, other sensors/device 310 may communicate with external device 306 using a first signal type (e.g. RF communication) but communicate with LCPs 302/304 using a second signal type (e.g. conducted communication). Further, in some examples, communication between devices may be limited. For instance, as described above, in some examples, LCPs 302/304 may communicate with external device 306 only through other sensors/devices 310, where LCPs 302/304 send signals to other sensors/devices 310, and other sensors/devices 310 relay the received signals to external device 306.

In some cases, communication pathway 308 may include conducted communication. Accordingly, devices of system 300 may have components that allow for such conducted communication. For instance, the devices of system 300 may be configured to transmit conducted communication signals (e.g. current and/or voltage pulses) into the patient's body via one or more electrodes of a transmitting device, and may receive the conducted communication signals (e.g. pulses) via one or more electrodes of a receiving device. The patient's body may “conduct” the conducted communication signals (e.g. pulses) from the one or more electrodes of the transmitting device to the electrodes of the receiving device in the system 300. In such examples, the delivered conducted communication signals (e.g. pulses) may differ from pacing or other therapy signals. For example, the devices of system 300 may deliver electrical communication pulses at an amplitude/pulse width that is sub-threshold to the heart. Although, in some cases, the amplitude/pulse width of the delivered electrical communication pulses may be above the capture threshold of the heart, but may be delivered during a blanking period of the heart and/or may be incorporated in or modulated onto a pacing pulse, if desired.

Delivered electrical communication pulses may be modulated in any suitable manner to encode communicated information. In some cases, the communication pulses may be pulse width modulated or amplitude modulated. Alternatively, or in addition, the time between pulses may be modulated to encode desired information. In some cases, conducted communication pulses may be voltage pulses, current pulses, biphasic voltage pulses, biphasic current pulses, or any other suitable electrical pulse as desired.

FIGS. 8 and 9 show illustrative medical device systems that may be configured to operate according to techniques disclosed herein. In FIG. 8, an LCP 402 is shown fixed to the interior of the left ventricle of the heart 410, and a pulse generator 406 is shown coupled to a lead 412 having one or more electrodes 408 a-408 c. In some cases, the pulse generator 406 may be part of a subcutaneous implantable cardioverter-defibrillator (S-ICD), and the one or more electrodes 408 a-408 c may be positioned subcutaneously adjacent the heart. In some cases, the LCP 402 may communicate with the subcutaneous implantable cardioverter-defibrillator (S-ICD). In some cases, the LCP 302 may be in the right ventricle, right atrium or left atrium of the heart, as desired. In some cases, more than one LCP 302 may be implanted. For example, one LCP may be implanted in the right ventricle and another may be implanted in the right atrium. In another example, one LCP may be implanted in the right ventricle and another may be implanted in the left ventricle. In yet another example, one LCP may be implanted in each of the chambers of the heart.

In FIG. 9, an LCP 502 is shown fixed to the interior of the left ventricle of the heart 510, and a pulse generator 506 is shown coupled to a lead 512 having one or more electrodes 504 a-504 c. In some cases, the pulse generator 506 may be part of an implantable cardiac pacemaker (ICP) and/or an implantable cardioverter-defibrillator (ICD), and the one or more electrodes 504 a-504 c may be positioned in the heart 510. In some cases, the LCP 502 may communicate with the implantable cardiac pacemaker (ICP) and/or an implantable cardioverter-defibrillator (ICD).

The medical device systems 400 and 500 may also include an external support device, such as external support devices 420 and 520. External support devices 420 and 520 can be used to perform functions such as device identification, device programming and/or transfer of real-time and/or stored data between devices using one or more of the communication techniques described herein. As one example, communication between external support device 420 and the pulse generator 406 is performed via a wireless mode, and communication between the pulse generator 406 and LCP 402 is performed via a conducted mode. In some examples, communication between the LCP 402 and external support device 420 is accomplished by sending communication information through the pulse generator 406. However, in other examples, communication between the LCP 402 and external support device 420 may be via a communication module.

FIGS. 8-9 only illustrate two examples of medical device systems that may be configured to operate according to techniques disclosed herein. Other example medical device systems may include additional or different medical devices and/or configurations. For instance, other medical device systems that are suitable to operate according to techniques disclosed herein may include additional LCPs implanted within or on the heart. Another example medical device system may include a plurality of LCPs without other devices such as pulse generator 406 or 506, with at least one LCP capable of delivering defibrillation therapy. In yet other examples, the configuration or placement of the medical devices, leads, and/or electrodes may be different from those depicted in FIGS. 8 and 9. Accordingly, it should be recognized that numerous other medical device systems, different from those depicted in FIGS. 8 and 9, may be operated in accordance with techniques disclosed herein. As such, the examples shown in FIGS. 8 and 9 should not be viewed as limiting in any way.

FIG. 10 is a flow diagram illustrating a method that may be carried out using implantable cardiac rhythm management system 10 (FIG. 1). First implantable device 12 may, in this example, be a subcutaneous implantable cardioverter while second implantable device 14 may be a leadless cardiac pacemaker. The method involves using data from the leadless cardiac pacemaker to improve performance of the subcutaneous implantable cardioverter. A first heart beat may be detected via the leadless cardiac pacemaker, as generally indicated at block 1010. As indicated at block 1020, the first heart beat may also be detected via the subcutaneous implantable cardioverter. An indication of the first heart beat detected by the leadless cardiac pacemaker may be communicated to the subcutaneous implantable cardioverter, as generally indicated at block 1030. As shown at block 1040, a blanking period may be initiated by the subcutaneous implantable cardioverter such that a T-wave of the detected first heart beat is blanked out by the subcutaneous implantable cardioverter so as to not be interpreted as a subsequent second heart beat. In some embodiments, the blanking period is configured such that a subsequent heart beat would be seen by the subcutaneous implantable cardioverter. This may help prevent a subcutaneous implantable cardioverter from counting the T-wave of the first heart beat as an R-wave of a subsequent heart beat. If a subcutaneous implantable cardioverter were to count the T-wave of the first heart beat as an R-wave of a subsequent heart beat, the subcutaneous implantable cardioverter would be effectively double counting heart beats, which could affect the therapy that is delivered.

In some instances, the second implantable device 14 may only conditionally send indications of detected heart beats to the first implantable device 12. For example, the second implantable device 14 may send indications of detected heart beats to the first implantable device 12 only under certain predetermined conditions, such as after it is suspected that the first implantable device 12 is and/or will be double counting heart beats. For example, in some cases, the first implantable device 12 may send an instruction to the second implantable device 14 to start sending indications of detected heart beats after the first implantable device 12 determines that it may be double counting heart beats. The first implantable device 12 may then send an instruction to the second implantable device 14 to stop sending indications of detected heart beats after the first implantable device 12 determines that it not double counting heart beats. In another example, the first implantable device 12 may send an instruction to the second implantable device 14 to start sending indications of detected heart beats when the first implantable device 12 determines that it is expected to deliver shock therapy in order to verify that the first implantable device 12 is not double counting heart beats. The first implantable device 12 may then send an instruction to the second implantable device 14 to stop sending indications of detected heart beats before actually delivering the shock therapy. These are just a few examples. In some instances, under most conditions the second implantable device 14 may not send indications of detected heart beats to the first implantable device 12, which can help extend the battery life of the second implantable device 14 and reduce communication traffic within the body.

Those skilled in the art will recognize that the present disclosure may be manifested in a variety of forms other than the specific examples described and contemplated herein. For instance, as described herein, various examples include one or more modules described as performing various functions. However, other examples may include additional modules that split the described functions up over more modules than that described herein. Additionally, other examples may consolidate the described functions into fewer modules. Accordingly, departure in form and detail may be made without departing from the scope and spirit of the present disclosure as described in the appended claims. 

What is claimed is:
 1. An implantable cardiac rhythm system comprising: a first implantable medical device configured to monitor a patient's heart rhythm and provide shock therapy to correct the patient's heart rhythm, the first implantable medical device further configured to detect a first heart beat of the patient from a first location; a second implantable medical device configured to sense the patient's heart, the second implantable medical device configured to detect the first heart beat of the patient from a second location; and wherein the second implantable medical device, upon detecting the first heart beat, communicates an indication of the detected first heart beat to the first implantable medical device, and in response, the first implantable medical device institutes a blanking period having a blanking period duration such that a T-wave of the detected first heart beat is blanked out by the first implantable medical device so as to not be interpreted as a subsequent second heart beat.
 2. The implantable cardiac rhythm system of claim 1, wherein the first implantable medical device comprises a defibrillator or cardioverter.
 3. The implantable cardiac rhythm system of claim 1, wherein the first implantable medical device comprises a subcutaneous cardioverter.
 4. The implantable cardiac rhythm system of claim 1, wherein the second implantable medical device comprises a leadless cardiac pacemaker.
 5. The implantable cardiac rhythm system of claim 1, wherein the second implantable medical device communicates with the first implantable medical device via conducted communication.
 6. The implantable cardiac rhythm system of claim 1, wherein the communicated indication of the detected first heart beat comprises an R-wave detection marker.
 7. The implantable cardiac rhythm system of claim 1, wherein the blanking period duration is set based, at least in part, upon a current heart rate detected by one or both of the first implantable medical device and the second implantable medical device.
 8. The implantable cardiac rhythm system of claim 1, wherein the blanking period duration is set based, at least in part, upon whether the detected first heart beat is an intrinsic heart beat or a paced heart beat.
 9. The implantable cardiac rhythm system of claim 1, wherein upon receiving the indication of the detected first heart beat from the second implantable medical device, the first implantable medical device continues to attempt to detect the first heart beat of the patient from the first location for a blanking time delay before instituting the blanking period.
 10. The implantable cardiac rhythm system of claim 1, wherein the blanking time delay is dependent upon a current heart rate of the patient.
 11. The implantable cardiac rhythm system of claim 1, wherein the first location is outside of the patient's heart and the second location is within the patient's heart.
 12. The implantable cardiac rhythm system of claim 11, wherein the first location is outside of the patient's chest cavity, and the second location is within a chamber of the patient's heart.
 13. An implantable medical device, comprising: one or more electrodes for detecting a heart beat of a patient; a receiver for receiving via conducted communication from another medical device an indication of a detected heart beat; and in response to receiving the indication of the detected heart beat, instituting a blanking period having a blanking period duration, wherein the implantable medical device is configured to not identify a subsequent heart beat of the patient via the one or more electrodes of the implantable medical device during the blanking period duration.
 14. The implantable medical device of claim 13, wherein in response to receiving the indication of the detected heart beat, the implantable medical device continues to sense for the heart beat of the patient for a blanking time delay before instituting the blanking period.
 15. The implantable medical device of claim 13, wherein the blanking period duration is set based, at least in part, upon a current heart rate of the patient.
 16. The implantable medical device of claim 13, wherein the blanking period duration is set based, at least in part, upon whether the detected heart beat is an intrinsic heart beat or a paced heart beat.
 17. The implantable medical device of claim 13, wherein the implantable medical device is a subcutaneous implantable cardioverter, and the another medical device is a leadless cardiac pacemaker.
 18. The implantable medical device of claim 13, wherein the received indication of the detected heart beat comprises an R-wave detection marker.
 19. A method of using data from a leadless cardiac pacemaker to improve performance of a subcutaneous implantable cardioverter, the method comprising: detecting a first heart beat via the leadless cardiac pacemaker; detecting the first heart beat via the subcutaneous implantable cardioverter; communicating an indication of the detected first heart beat detected by the leadless cardiac pacemaker to the subcutaneous implantable cardioverter; and initiating a blanking period by the subcutaneous implantable cardioverter such that a T-wave of the detected first heart beat is blanked out by the subcutaneous implantable cardioverter so as to not be interpreted as a subsequent second heart beat.
 20. The method of claim 19, wherein the blanking period is configured such that a subsequent heart beat would be seen by the subcutaneous implantable cardioverter. 